The subject matter disclosed herein relates to X-ray tubes, and in particular, to X-ray cathode systems for use in X-ray generation.
Various types of medical imaging systems and treatment systems (e.g., radiation therapy systems) generate X-rays as part of their operation. For example, with respect to imaging techniques, those based on the differential transmission of X-rays include, but are not limited to, fluoroscopy, mammography, computed tomography (CT), C-arm angiography, tomosynthesis, conventional X-ray radiography, and so forth. X-ray generation in such contexts is generally performed using an X-ray tube. X-ray tubes typically include an electron emitter, such as a cathode, that releases electrons at high acceleration. Some of the released electrons impact a target anode. The collision of the electrons with the target anode produces X-rays, which may be used in a suitable imaging or treatment device.
In thermionic cathode systems, a filament is present that releases electrons through the thermionic effect, i.e. in response to being heated. One challenge in such systems is providing long electron emitter life along with high beam current. In particular, high beam current is generated by heating an emitter to high temperatures—approaching 2600 C. At these temperatures the emitter material, typically metal (e.g., tungsten), evaporates. The rate of evaporation increases as the temperature increases. Thus, the useful life of an electron emitter of an X-ray tube may be limited, particularly in high beam current usage.